"""SIP credential provisioning for ring-group workers (§5.3).

Workers exist only as SIP endpoints — no product accounts. The dashboard shows
generated credentials + a QR code for quick softphone setup (Linphone/Zoiper/
Groundwire all accept manual entry; the QR encodes a standard sip URI plus the
fields spelled out).
"""

from __future__ import annotations

import io
import re
import secrets

from gogo.config import get_settings


def make_sip_username(tenant_slug: str, worker_name: str, suffix: str | None = None) -> str:
    base = re.sub(r"[^a-z0-9]+", "", worker_name.lower())[:12] or "radnik"
    suffix = suffix or secrets.token_hex(2)
    return f"{tenant_slug[:16]}-{base}-{suffix}"


def make_sip_password() -> str:
    return secrets.token_urlsafe(12)


def sip_domain() -> str:
    """SIP registrar host — derived from base_url; overridable later if split hosts."""
    from urllib.parse import urlparse

    return urlparse(get_settings().base_url).hostname or "localhost"


def provisioning_text(sip_username: str, sip_password: str) -> str:
    """Payload for the QR code: sip URI + explicit fields (readable by humans too)."""
    domain = sip_domain()
    return (
        f"sip:{sip_username}@{domain}\n"
        f"Server/Domain: {domain}\n"
        f"Username: {sip_username}\n"
        f"Password: {sip_password}\n"
        f"Transport: UDP 5060"
    )


def qr_png(payload: str) -> bytes:
    import qrcode

    img = qrcode.make(payload)
    buf = io.BytesIO()
    img.save(buf, format="PNG")
    return buf.getvalue()